Search for Correlated High Energy Cosmic Ray Events with CHICOS

We present the results of a search for time correlations in high energy cosmic ray data (primary $E > 10^{14}$~eV) collected by the California HIgh school Cosmic ray ObServatory (CHICOS) array. Data from 60 detector sites spread over an area of 400~km$^2$ were studied for evidence of isolated events separated by more than 1~km with coincidence times ranging from 1~$\mu$sec up to 1~second. The results are consistent with the absence of excess coincidences except for a $2.9 \sigma$ excess observed for coincidence times less than 10~$\mu$sec. We report upper limits for the coincidence probability as a function of coincidence time.